Chemical versus physical pressure effects on the structure transition of bilayer nickelates

作者：Gang Wang, Ningning Wang, Tenglong Lu, Stuart Calder, Jiaqiang Yan, Lifen Shi, Jun Hou, Liang Ma, Lili Zhang, Jianping Sun, Bosen Wang, Sheng Meng, Miao Liu, Jinguang Cheng · 发表于：npj Quantum Materials · 年份：2025 · DOI：10.1038/s41535-024-00721-8 · 被引用次数：29 · 研究领域：Advanced Condensed Matter Physics、Magnetic and transport properties of perovskites and related materials、Rare-earth and actinide compounds

Abstract The observation of high- T c superconductivity (HTSC) in concomitant with pressure-induced orthorhombic-tetragonal structural transition in bilayer La 3 Ni 2 O 7 has sparked hopes of achieving HTSC by stabilizing the tetragonal phase at ambient pressure. Chemical pressure, introduced by replacing La 3+ with smaller rare-earth R 3+ has been considered as a potential route. However, our experimental and theoretical investigation reveals that such substitutions, despite causing lattice contraction, actually produce stronger orthorhombic distortions, requiring higher pressures for the structural transition. A linear extrapolation of P c versus the average size of A -site cations (< r A >), yields a putative critical value of < r A > c ≈ 1.23 Å for P c ≈ 1 bar. The negative correlation between P c and < r A > indicates that replacing La 3+ with smaller R 3+ ions is unlikely to reduce P c to ambient pressure. Instead, substituting La 3+ with larger cations like Sr 2+ or Ba 2+ might be a feasible approach. Our results provide guidance for realizing ambient-pressure HTSC in bilayer nickelates.